This application relates to an arrangement where a gas turbine engine can bypass a drive for a propulsor.
Gas turbine engines are known, and have typically included a fan delivering air into both a bypass duct as propulsion, and into a core engine. The air leading into the core engine is compressed in a compressor section, mixed with fuel in a combustor section, and ignited. Products of this combustion pass downstream over turbine rotors, driving them to rotate. The turbine rotors in turn mechanically drive the fan and compressor.
While this basic arrangement has proven successful, future aircraft designs require more flexibility.
In addition, most gas turbine engines have a very large fan delivering a high volume of air through the bypass duct, and rearwardly of the aircraft. This makes it difficult to operate the engines while the aircraft is sitting at an airport gate. Thus, it is known to provide an auxiliary power unit (APU) on an aircraft to provide power prior to starting the main gas turbine engine for the aircraft. The APU is essentially a small gas turbine engine that is relied upon to provide power such as from electrical generators prior to the main gas turbine engine starting.